1. Field of the Invention
This invention pertains generally to the field of solid waste disposal, and in a most preferred embodiment to commercial roof removal and disposal.
2. Description of the Related Art
One of the most basic necessities of mankind has long been known to be that of shelter. A common phrase which describes this need is simply that of “a roof over your head.” The primary purpose of this roof is to keep the elements from entering from above and adversely affecting the contents and occupants of a building. First and foremost among the elements to be kept out is moisture.
Many early roofs were simply leaves, thatch, or the like. Such roofs were not resistant against high winds, and would invariably, frequently and unpredictably leak. With proper slope and enough plant matter, it is certainly possible to construct a roof that does not leak. However, most plant matter is not amenable to being securely anchored in a way which will reliably keep water out during high winds and storms. Furthermore, plant matter decays at a relatively high rate, making it difficult to construct a roof with a reasonably long life expectancy. In addition, plant matter is prone to infestation by insects and animals, which in turn greatly accelerate damage and the rate of failure.
Throughout the ages, there have been many advances in nearly every part of living, and nearly all of these are dependent in some degree or another upon that same basic necessity that we generally describe as shelter. In the modern era in which we live, there are few possessions of people that can withstand exposure to moisture. This is particularly true with modern conveniences, such as electrical lighting, computers, appliances and the like. Many interior building materials are equally as susceptible to damage by moisture. In fact, long term or frequent exposure to moisture can literally destroy an entire building, even if individual possessions remain protected therein.
As may be apparent, roofs are vital for a number of reasons, and form one critical basis of our modern society. As may be appreciated then, there has been an enormous amount of technology and time applied to the development of suitable roofing for each of the many applications that civilization demands. Asphalt shingles are common in residential roofs, where the roof will slope at a significant angle. The benefit of this slope is an improved shedding of water, snow, and ice, ensuring that as long as the shingles are overlapping in a fish-scale fashion the water, snow, or ice will not travel backwards against the force of gravity. In turn then, as long as the shingles do overlap properly, no water will reach the roof underlayment and so the building will stay dry. When a problem arises, such as the loss of a shingle, it is often readily visible. Appropriate measures may then be taken to replace either one or a few shingles. If instead the failure was caused by aged shingles that have become brittle or are otherwise no longer serviceable, then the shingles are torn off and replaced in entirety. While asphalt shingles are most common, other shingle materials in use include fiberglass, cedar, slate, metals such as steel and copper, and even clay.
This has worked well for the relatively smaller sizes of individual residential roofs. While the slope adds somewhat to the overall cost of the building, additional sheltered space or even upper level rooms are commonly located in the attic directly below the roof, thereby benefitting the home occupants with extra useful space. When an excessive quantity of snow falls onto the roof, a homeowner may simply scrape the snow from the roof using a roof rake or the like. In some instances, where a great enough slope exists, the snow will slide off by itself, or when the weather warms, the snow will melt or slide off.
In contrast to a residence, many commercial buildings are much larger, having many times the square footage to be covered. Moreover, with a commercial building, the building owner is not responsible just for the safety of the owner, but also for the safety of many other individuals as well. Features that are acceptable in individual residences are no longer acceptable in commercial buildings. Moreover, owing to the size differential, features that would be harmless in residential applications can prove to be downright dangerous and life threatening in a larger commercial building. Consider for example the case of a simple icicle, which is commonly seen in the moderate and northern latitudes during the colder months. An icicle which breaks and falls from an eight-to-ten foot height presents little hazard to a person walking thereunder. A small clunk is all that may be reasonably expected. However, if the icicle is falling from a ten story or higher commercial building, the icicle could be truly hazardous. The same is true of wet and heavy snow or packed icy snow that may at times accumulate on a roof. Using the standard residential construction, a person might be buried or even killed by large quantities of snow and ice sliding from a large commercial roof. As a result, few commercial roofs are sloped like a residential roof. When they are sloped, they will most commonly be sloped at great degree such that there will be no chance of accumulation. Even in these situations, the high volumes of water that will be shed from a large roof onto the perimeter of the building, even in relatively gentle rains, might be likened to walking into a waterfall. If for this reason if no other, a sloped roof over a large building is usually highly undesirable and unpleasant. Consequently, most frequently a commercial roof is designed in a completely different way from a residential roof. First, the roof is most typically relatively flat, with only a minor slope. The slope will most commonly lead to a drain that might lead in many cases directly to a storm sewer or the like, such that any run-off from the roof is directed through pipes directly to a municipal storm system or other suitable drain. This generally flat surface normally terminates at a level below the building sides, often times several feet below. When precipitation falls upon the roof, it will either be directed through gentle slope into the drain, or if in the form of snow or ice, it will simply accumulate on the top of the roof until warmer weather arrives.
Since the commercial roof necessarily does not have the benefit of slope found in a residential roof, the materials used in the fabrication thereof differ in several very significant ways. Most consequentially, the commercial roof must behave like a swimming pool liner, and serve as a total water barrier for standing water which might accumulate thereon. The roof must also be quite robust, and be able to withstand the weight of many pounds per square inch of accumulated water, snow or ice. There will be very wide temperature extremes, not only with the extreme cold but also with summer sun and heat, and little direct air movement owing to the building walls forming a ledge. Finally, the commercial roof will be exposed to periods where water is contained therein, and other periods where the roof is simply dry and parched like a desert.
Ordinary residential shingles are designed simply to shed water, passing the water down to the next shingle, until there are no more shingles and the water falls from the roof. In contrast, a commercial roof must contain the water through all extremes. As a result, commercial roofs are much more complex than simple residential shingles. Common commercial roofing materials will generally include some combination of insulation layers, tar, rubber or elastomeric water barriers, and smaller rocks or pebbles. Common types of low sloped roofing for industrial/commercial structures include the built-up-roof (BUR), modified bitumen, Sprayed-in-Place Polyurethane Foam (SPUF), and/or membrane layers which often consist of plies of polymers or elastomers, such as EPDM, CSPE, PVC, and TPO.
The built-up-roof (BUR) comprises multiple plies of asphalt saturated organic felt or coated fiberglass felts. The individual plies of felt are adhered with hot asphalt, coal tar pitch or adhesive. The modified bitumen roof is heat welded, asphalt adhered or installed with adhesive. In this roof, asphalt is mixed with polymers such as Atactic Polypropylene (APP) or Styrene Butadiene Styrene (SBS), then applied to fiberglass and/or polyester mat, and seams are sealed by locally melting the asphalt with heat, hot mopping of asphalt, or adhesive. Sprayed-in-Place Polyurethane Foam (SPUF) is simply foam sprayed in-place on the roof, and then coated with a wide variety of coatings, or in some instances, covered with gravel.
Since the introduction of elastomeric and polymer flexible-sheet membranes some thirty years ago, membrane roofing materials now comprise more than half of the commercial roofing market. There are a wide variety of membrane materials, including both thermosetting plastics and rubbers and thermoplastic materials. EPDM (ethylene propylene diene monomer) rubber membranes; PVC (polyvinyl chloride); TPO (ThermoPlastic Olefin); and CSPE (chlorosulfonated polyethylene) synthetic rubber are all commonly used. As but one example of the complexity of these modern materials, TPO is a trade name that refers to polymer/filler blends usually consisting of some fraction of polypropylene, polyethylene, block copolymer polypropylene, rubber, and a reinforcing filler. Common fillers in this TPO blend include talc, fiberglass, carbon fiber, wollastonite, and Metal Oxy Sulfate. Common rubbers in a TPO blend include ethylene-propylene rubber, EPDM, ethylene-octene, ethylene-butadiene, and styrene-ethylene-butadiene-styrene. There are an ever-increasing variety of commercially available rubber and block copolymer polypropylene material available which are incorporated into TPO.
These materials are used to cover large areas of buildings. Unfortunately, when the materials fail, such as might be due to unavoidable aging, leaks or precursor cracks may develop that require repair or replacement. As already noted, these roofs are often quite large, covering a great many square feet. Furthermore, the roofing material is usually quite heavy, making the task of removing the old material from the roof quite daunting. Finally, there are a very wide variety of materials used in the fabrication of these roofs, as noted above.
In the prior art, the task of commercial roof removal has been accomplished by cutting smaller sections of the material off, stacking it into wheel barrows and the like, and manually hauling it to be loaded into some type of waste container. For shorter buildings, the wheelbarrow might simply be dumped over the edge of the roof into a waiting roll-off container or the like. With taller buildings, it may be necessary to set up some type of boom, crane or other structure to lower containers of the waste material from the roof. In either case, the manual labor is intensive, and the risk of work-related injury undesirably great.
Regardless of the method of removal, the roofing material is next disposed of as ordinary waste in a landfill or the like, using up valuable land resource and not recovering any value from the materials being disposed of. Furthermore, the waste containers themselves are only partially filled, owing to the irregular stacking that inevitably occurs from the slabs and small rolls of the material being dropped irregularly into the container. Consequently, the waste dumping fees are undesirably higher due to the state of the material.
To overcome the limitations of the manual methods of removal and disposal of roofing materials, several shingle grinders have been devised, as illustrated in a number of U.S. Pat. Nos. including 5,201,472 to Brock; 5,385,426, 5,386,947 and 5,451,003 to Omann, the contents and teachings of each which are incorporated herein by reference. Each of these patents illustrate the use of hammer mills, which are effective with more brittle materials, but relatively ineffective when applied to elastomers and the like. Consequently, while the methods proposed therein may have much utility for the grinding of residential asphalt shingles, little teaching is provided for handling the far more diverse materials, including elastomers and polymers as well as asphalt and rock found in commercial roofing. Furthermore, these patents do little to provide a reasonable approach for removing material from a large commercial roof.
Another patent of interest, which introduces the concept of a grinder in combination with a blower is U.S. Pat. No. 3,658,267 to Burwell, entitled “Apparatus for Disintegrating Tires and the Like.” This patent, the teachings which are incorporated herein by reference, illustrates a tire grinding apparatus that reduces the tires down to a powdered form prior to sucking the dust out through a vacuum. Once again, the method used to reduce the rubber is of little applicability to commercial roofing material, since it would almost immediately clog from the asphalt and similar content. Furthermore, the teaching of transporting rubber dust provides little benefit to the roofing industry, where again asphalt and other components will tend to agglomerate any dust.
U.S. Pat. Nos. 3,850,364 to Robbins and 6,086,002 and 5,454,521 to Frazier et al, the teachings of each which are incorporated herein by reference, disclose a grinder in combination with a fan to drive comminuted material to and through a discharge chute. However, these patents are for lawn debris and plant matter instead of rubber and asphalt, and so like Burwell treat material with very different characteristic than the rubber, asphalt and rock combination of commercial roofing.
Other patents pertaining methods for comminuting rubber, for which the teachings are incorporated herein by reference include U.S. Pat. Nos. 2,853,742 to Dasher; 3,190,565 to Jayne, Jr.; 5,115,983 to Rutherford, Sr.; 5,782,417 to Niederholtmeyer; 5,904,305 to Kaczmarek; and 5,927,627 to Edson et al. As with the other references already described, these methods and apparatus are not applicable to the complex roofing material used in commercial roofs, which typically includes some combination of rubbers and polymers, asphalt and rock.
There are several methods which are, in fact applicable to the complex roofing materials found on commercial roofs. The include cryogenic cooling of the materials prior to grinding, such as for exemplary purposes illustrated in U.S. Pat. Nos. 3,633,830 by Oberpriller and 5,533,680 by LaGrone, the teachings which are incorporated herein by reference. U.S. Pat. No. 5,337,965 by Chiovitti illustrates another approach, the teachings which are incorporated herein by reference, that of solvent immersion. As may be readily understood, both cryogenic cooling and solvent immersion are undesirably expensive, complex, and less safe than a direct grinding process. The solvent system also introduces a new waste issue, with regard to the proper separation and handling of the solvent. Consequently, while operative, neither the cryogenic or solvent systems are suitable for large scale application to the removal of commercial roofing materials.